Extensible boom with load level maintenance means



Dec. 29, 1959 c. H. RAYMOND EXTENSIBLE BOOM WITH LOAD LEVEL MAINTENANCE MEANS Filed Aug. 10, 1956 3 Sheets-Sheet l Dec. 29, 1959 c. H. RAYMOND 2,919,036

EXTFNSIBLE BOON WITH LOAD LEVEL MAINTENANCE MEANS Filed Aug. 10, 1956 3 Sheets-Sheet 2 J H '0 "VINE fl! In I a 2d @3 1; iv Wm wm g w POI ww R 8 3 1 3 M 8 W IIIIIIIIIII/lI/IIII/A M N W ac NW. NW

ow mm mm W ovxw N l 6 wl 0% om, mm mm Qm NM. Mb @w Dec. 29, 1959 c. H. RAYMOND EXTENSIBLE BOOM WITH LOAD LEVEL MAINTENANCE MEANS Filed Aug. 10, 1956 3 Sheets-Sheet 3 711/ Fil java i? ,omiffij United States Patent EXTENSIBLE BOOM WITH LOAD; LEVEL MAINTENANCE MEANS Clifford H. Raymond, Chicago, Ill. 7 Application August 10, 1956, Serial: No. 603,266

9,-Claims. 01. 212-35 This invention relates to extensible boom with load level maintenance means more particularly for truck cranes or, the like.

In truck cranes having, load. carrying cables running from a winch over a telescoping boom and terminating atthe, load it is necessary to manipulate two levers when extending andv contracting the boom while maintaining the loadlevel. One lever controls the winch which retracts and pays out the cable and another controls extension and contraction of, the boom. The present invention eliminates the necessity for actuating both control levers and provides automatic compensating means for maintaining the load at a given level while the boom is. being contracted or extended, thus requiring the operator. merely to actuate the lever for controlling the extension of the boom without manipulating the winch lever, with a corresponding economy of time and labor.

One important application of the present invention is in connection with. truck cranes that are employed to load cargo such as bombs, for example, into airplanes. When the crane picks up a load and brings it to the vicinity of the plane it maybe desirable that the boom of the crane be projected into the cargo receiving door of, the plane. and thus into the cargo receiving compartment thereof. Marked savings in time and labor of loading a plane maybe saved by the present invention, because as the boom is extended. through the door of, the. plane, the load carried on thecable is automatically maintained at, a constant level so as to make its entry through the door readily possible. by mere extension of the. boom without manipulation of the, cablewinch.

The. invention will be readily. understood by reference to the following description, taken together with the accompanying drawings, of an illustrative embodiment of the invention, and inwhich. drawings:

Figure l is:a general view of a truck crane embodying the present invention, the. boom being shown. retracted in full lines. and extended in broken lines;

Figure 2. is an enlarged longitudinal section of the boom, the boom being shown retracted;

Figure 3 is a plan section of the boom as shown in Fig. 2;

Figure 4' is an enlarged cross-section taken on the line 44 of Fig. 2, but for clearness omitting the hydraulic means for extending and retracting the boom;

Figure, 5 is a similar crosssection taken on the line v5-5 of Fig. 2;

Figure 6 is asimilar cross-section taken on the line Figure 7 is a similar crossesection taken on the line of Fig. 2; and:

Figure 8 is, a. view somewhat similar to Fig. 2, but on 'a somewhat smaller scale, in a position with the boom corresponding .to Fig. 8;

I 2,919,036 Patented Dec. 29, 1959 Figure 10 is an enlarged cross-section taken on the line 1Q-10 of Figure 8;

Figure 11 is a similar cross-section taken on the line 1111 of. Figure 8; v

Figure 12 is a similar cross-section taken on the line 12-1 2 of Figure 8.; i

Figure 13 is a schematic view corresponding generally to the position of the boom shown in Fig. 2; and

Figure 14 is a similar schematic view corresponding generally to thepartially extended, position of the boom shown in Fig. 8.

Referring in detail to the illustrative construction shown in the drawings; the numeral 21 represents in general a truck crane having the usual cab 22 and body platform 23 0. which adjacent the cab is suitably mounted a control mast 24 carrying a boom indicated generally by the numeral 25. In this instance the boom is formed of a pain of hollow telescoping sections preferably of rectangular cross-section. The boom 25 is hereshown swivelly mounted on the mast 247 as by being horizontally pivoted at; 26 on the mast head 27 that is itself rotatable on a vertical axis with respect to the mast 24. The boom 25 is extensible; and contractable as by having a female or' a proximal section 28 and a. male or distal section 29 telescoping into. the proximal section 28. The proximal section 28, being the section carrying the pivot shaft 26,, is; reinforced; adjacent the head 27 by a pair of depending gusset, plates 30 and diagonal braces 30a.

For elevating. the. boom 25. (which position is not here shown) on its. pivot 26,, afluid jack is provided having a cylinder. 31 that is articulatedv at 32 with a pair of lugs 33 extending from the. head 27, and. having a plunger or piston. rod 34 that-is articulated at 35. with a pair of brackets 36 (Fig. 10) rigid with the gusset plates 30. The gusset plates. 30 may haveregistering openings 37 therein. for access to. the pin, 38 that passes. through the knuckle 39 at the outer end of the piston rod. 34.

Between the gusset plates 30 is mounted a cable winch reel, 40 that is operated by a. hydraulic motor reducer 41 carried. on one side of the proximal boom member 28 (Fig. 3). i

A group ofv control levers denominated collectively by the-letter. P are shown carried bythe mast head 27. These levers (which. need not. be. individually identified) may be. as follows: one forv controlling the jack 31 to elevate the boom 25; one for controlling the cable winch motor 41 to wind up or pay out cable; one for rotating the mast head 27 on a vertical axis by means which may include. a hydromotor shown schematically at 42 located with its. shaft 42a on a vertical axis within the mast 24; and one for controlling the hydraulic jack means (later described) forextending and retracting the boom 25.

In accordance. with the present invention the winch 40 has entrained thereon for extension and retraction, a loadncarrying cable indicated generally by the numeral 43, the outer or terminal end of the cable being anchored at 44,to the. outer end of the proximal boom member 28 through the. intermediation of a pair of brackets 45 (Figs. 2 and 5) which receive therethrough a pintle 45a with which a clevice 45b securely attached .to the cable 43 is articulated.

Cable. 43 has a run 46 that extends forwardly to an idler sheave 47 carried in the. hollow interior of the proximal boom section, 28, and also within the interior of the distal boom section 29 as later explained. Trained over the sheave 47 the cable 43 has a run 48 that extends rearwardly over a traveling sheave 49- that is carried within the hollow interior of the boom section 29 adjacent the rear end thereof and that travels with boom section :29. Trained over the sheave 49 the cable 43- has a run 50 that extends forwardly to one of a pair of sheaves 51 that are joumalled in the hollow interior of the distal section 29 at the outer or forward end thereof and that also travel with this boom section. Trained over the sheave 51 the cable 43 extends downwardly to a pulley block 53a and around one of a pair ofsheaves 53 carried by this pulley block, back up over the other sheave 51 carried at the outer end of the distal boom section 29, back again down to the pulley block 53a, around the other sheave 53 carried by the pulley end). When the high pressure side of the line by means of one of the control levers P is'connected with inlet 85, the piston rods are propelled outwardly to extend the boom and when the high pressure side is connected with the inlets 86 the piston rods are moved in the opposite direction to retract the boom.

Figures 8 and 9 which are on-a slightly reduced scale from Figures 2 and 3 show the boom partially extended from the position of the previous figures, but, in accordance with the present invention, the position of the load hook 76 suspended from the pulley block 53 is at the same elevation from the truck platform 23 in both Figs. 2 and 8. This remains true even when the boom is fully exthe sheave 55 the cable 43 has then a run 56 which ends i in the termination 44 heretofore referred'to and which is anchored to the proximal boom section 28.

As shown, the proximal boom section 28 has in its lower surface an elongated longitudinal slot 57 and the distal boom section 29 has in its lower surface the registering but longer elongated longitudinal slot 57a that is wider at 5712, the cable run 46 passing through the slots 57 and 571) between the reel 40 and the sheave 47.

Means for rotatably mounting the sheaves 47, 55 and 51, are best seen in Figs. 2 and 4. The sheave 47 is mounted on an arbor 58 that is carired by a pair of upstanding lugs 59 that are secured to the underwall 60 of the proximal boom section 28 and that pass through the slot 57b in the lower wall of the distal boom section 29.

As best seen in Figs. 2 and 6 the sheave 55 is mounted of an arbor 61 that is carried by a pair of depending lugs 62 that hang from a plate 63 that is secured on the lower face of the distal boom section 29, partially closing the slot 57b, just short of the outer end of this boom section I a.

and spaced from said end so as not to interfere with the downwardly extending runs 52 of cable 43 that support the pulley block 53a. As best seen in Figs- 2 and 7 the sheaves 51 are mounted on a spindle 64 that is journaled .inla pair of vertical web members 65 that are spaced apart laterally in the outer end of the distal boom section 29, the boom section having a pair of registering openings 66 in its side walls. by which access may be obtained to the spindle 64. As best seen in Figs. 8 and 11 the sheave 49 is mounted on an arbor 67 that is carried by a pair of vertical web members 68 that are secured within the distal boom section 29 adjacent its rear end.

The boom sections 28 and 29 are preferably of hollow rectangular cross-section and in this instance of approximately square cross-section with the boom section 29 being telescoped within the boom section 28. For antifriction purposes, as best seen in Figs. 2 and 5 the boom section 28 carries a roller 69 axled on pintle 70 that is carried by the brackets 45 depending from the lower wall of the boom section 28 and that plays in an opening 71 in the lower wall of the boom section 28 to have the boom section 29 ride thereon. Similarly and conversely, as best seen in Figs. 8 and 12 the boom section 29 carries a roller 72 on pintle 73 jou'rnaled in bosses 74 on the opposite inner walls of the boom section 29 projecting through an opening 75 in the upper wall of the boom section 29 so that the boom section 28 rides thereon.

As seen in Figs. 8 to 12 inclusive, means for extending and retracting the boom 25 are here shown as a pair of double acting hydraulic jacks housed within the hollow telescoping boom sections, each jack comprising a cylinder 79, and a plunger or piston rod 80, lying alongside the .traveling sheave 49 and between which this sheave and its webmountings 68 travel when the boom is extended and retracted. Each cylinder is carried at its proximal .end by bolts 81 on a cross bar 82 secured to the proximal boom section 28. Each piston rod 80 at its outer end is articulated with a wrist pin 83 each of which is mounted between a web member 84 and an adjacent wall of the boom section 29 respectively. Each cylinder is desirably double-acting as by having the hydraulic line con tended for example as shown in Fig. 1 with the outer end of the boom overhanging the end of the truck body 23. The principle of operation to obtain this advantageous result is as follows, reference being had particularly to the schematic Figures 13 and 14: v

Let .it be assumed that Fig. 13 corresponds diagrammatically to'the position of the boom in Fig. 2 and Fig. l4.corresponds to the boom in Fig. 8. Since the proximal boom section 28 is horizontally relatively fixed with respect to the truck 21, this is true also of the winch reel-40 and the sheave 47 both of which are fixed with respect to the boom section 28. It is true also of the anchorage point 44, the terminal end of the cable which is on the boom section 28. Sheaves 49, 51, 53 and 55, however, being carried by the extensible boom sec- .tion, 29 are relatively movable with respect to the boom section 28 and the truck body. This is true also of the loadrepresented by the letter W which it may be assumed has for the time being a fixed anchorage at its proximal end on the winch reel 40.

When, now, the boom'is extended as for example from the position of Fig. 13 to that of Fig. 14, by sliding the distal boom section 29 outwardly of the proximal boom section 28 from say the position of the distal boom section shown in Figs. 2 to the position shown in Fig. 8, the sheave 49 moves from the position A to the position A, or the distance y, thus reducing the length of the run 48 of the cable by this amount. The distance between the reel 40 and sheave 47 cannot vary and this is true also of the distance between the sheave 49 and the sheave 51. If the length of the run 56 be increased by the same amount y that the run 46 is decreased or by the amount x the ,sum of the lengths 52 and 54 will remain the same. If the sum of the lengths 52 and 54 remain the same, the

sheaves 53 will maintain the same level, since by the action of gravity the pulley block 53a will maintain its same relative position with respect to the sheaves 51 and 55. Since the positions of sheaves 49,51 and 55 are all relatively fixed on the same boom section 29, when the sheave 49 moves from A to A the sheave 55 will move the same distance from B to B or the distance x. Therefore, y and x are equal. In other words, assuming no rotation of the winch reel 40, an overall length of the cable 43 from the winch 40 to the anchorage point of its terminal end 44 is the same whether the boom be contractedto the position of Fig. 13 or be extended Differences in the lengths of the runs 48 and 56 are compensatory, which is to say that for any given reduction or increase in the length of the run 48, the run 56 has the same inverse increase or reduction, thus maintaining the lengths of the runs 52 and 54 the same in all cases, that is in all'positions of the extension or retraction of the boom, and keeping the load W at the same level.

It will of course be understood that what has just been described will be true in any angular position of the boom whether on a horizontal are or. on a vertical. arc,

so long as reel 40 be not rotated, since the reel, cable and sheaves move with the boom.

It will of course be further understood that if it be desired to increase the length of the cable 43 from the winch reel 40 to its terminal end 44, for example, first to pick up a load W from the fioor of the truck body 23 and-lift it to the position as shown in Fig. 1, the reel 40 may be manipulated or rotated by manipulation of one of the control levers P, that is, the appropriate lever to rotate the winch, first to pay out cable and then to draw it in again by reason of which the elevation of the load hook 76 will be changed accordingly.

By means of the present invention, the load W may be picked up from the. floor of the. truck body 23 by manipulation of the winch reel 40 to rotate the latter first to lengthen the cable 43 to pick up the load and then to shorten the cable to raise it to the elevation E shown diagrammatically in Fig. I, then without manipulation of the winch reel the boom 25 may be extended simply by manipulation of the appropriate control lever P for that purpose, and the load W may be moved through the doorway T for example, the load maintaining the same elevation E during this movement, then by manipulation of the winch lever the cable may be lengthened to lower the load W to the floor 78 of the doorway T.

So constructed and arranged, there is here provided means by which the boom may be extended or contracted while maintaining the load carried by the load carrying cable at a constant elevation. This is accomplished without manipulating the cable winch, and includes automatic means for maintaining a constant length for the load carrying cable measuring from the winch to the end of the cable regardless of the relative position of the boom sections. This desirable result is accomplished, in the illustrative example here given, by the system of cable sheaves here described and the anchoring of the terminal end of the cable to the fixed boom section so that when one end is pulled in the other end is payed out, or vice versa.

A similar result could be accomplished if for example the terminal end of the cable were anchored to the distal boom section 29 and for every foot of outward movement of the sheave 51 the sheave 49 were caused to move outwardly a distance of one-half foot. The simplicity and efficiency of the arrangement here shown is however preferred but it is. to be understood that the invention is not intended to be limited to the specific arrangement here shown or to details of construction shown for purposes of exemplification and furthermore it may not be essential at all times to employ all features of the invention conjointly since various combinations or subcombinations may at times be advantageously employed, and that such changes including modifications or additions may be made as fall Within the scope of the appended claims without departing from the invention.

What is here claimed is:

1. An extensible boom assembly for moving a load along a constant level path including an inner boom section mounted on a supporting structure, an outer extensible and retractable boom section, means for extending and retracting the outer boom section, a cable winch on the inner boom section, a first guide on the inner boom section spaced outwardly from the winch, a second guide near the inner end of the outer boom section, a third guide near the outer end of the outer boom section, a fourth guide near the outer end of the outer boom section, a cable attaching means on the inner boom section, a cable wound on the winch and then extending outwardly to the first guide, inwardly to the second guide, outwardly to the third guide, over the fourth guide, and inwardly to the attaching means where it is secured, and a load carrying device suspended from the cable between the third and fourth guides, said load carrying device adapted to ride along the cable at a constant elevation as the extend- 6 ing and retracting means moves the outer boom section inwardly and outwardly.

2. The extensible boom assembly of claim 1 further characterized in that the inner and outer boom sections are telescopically arranged so that one is received within the other when the extending and retracting means positions the outer boom section.

3. The extensible boom assembly of claim 2 further characterized in that the inner and outer boom sections have a rectangular cross-sectional configuration, and further including first anti-friction means carried by the outer boom section and second stationary anti-friction means carried by the inner boom. section, each anti-friction means bearing against the other section in direct bearing engagement as the outer boom section extends and retracts.

4. The extensible boom assembly of claim 1 further characterized by and including boom assembly elevating means for elevating and maintaining the boom assembly in a preselected position during operation of the outer boom section.

5. The extensible boom assembly of claim 1 further characterized in that the fourth guide is positioned inwardly of the third guide on the outer boom section at a point between the third guide means and the cable attaching means to thereby provide a two point support for the cable which supports that portion of the load carrying device.

6. The extensible boom assembly of claim 5 further characterized in that the load carrying device includes a fifth guide adapted to be rotatably received in a cable loop formed between the third and fourth guide, said load carrying device having sufiicient weight to maintain the fifth guide below the fourth guide.

7. An extensible boom assembly for moving a load along a constant level path including an inner boom assemblage having an inner boom section mounted on a supporting structure, an outer extensible and retractable boom section, means for extending and retracting the outer boom section, a winch on the inner boom assemblage, a first guide on the inner boom assemblage spaced outwardly from the winch, a second guide on the outer boom section, said second guide being inwardly spaced from the first guide in all positions of the outer boom section with respect to the inner boom assemblage, a third guide outwardly spaced from the second guide on the outer boom section, flexible strand attaching means on the inner boom assemblage, a flexible strand having in effect a fixed length for any position of the winch, said strand having its inner terminal end wound about the winch and then running outwardly to the first guide, inwardly to the second guide, outwardly to the third guide, and inwardly to the attaching means where its outer terminal end is secured, said winch being so positioned that the run of flexible strand between the winch and first guide lies substantially parallel to the path of travel of the second and third guides, and a load carrying device suspended from the cable between the third guide and the attaching means, said load carrying device adapted to ride along the cable at a constant elevation as the extending and retracting means moves the outer boom section inwardly and outwardly.

8. An extensible boom assembly for moving a load along a level path, said assembly including an inner boom section and an outer extensible and retractable boom section, a supporting structure for the inner boom section, said inner boom section and its supporting structure being fixed with respect to the outer boom section, means for extending and retracting the outer boom section, a winch secured to the fixed portion of the boom assembly, and automatic compensating means for maintaining a load carried by the outer boom section at a constant level without manipulation of the winch during extension and retraction of the outer boom section, said means including a plurality of flexible strand guide means arranged to maintain a flexible strand entrained therearound in a non-slack condition inall relative positions of the-inner and outer boom sections including afirst guide means positioned on the fixed portion of the boom assembly, a second guide means positioned on the outer boom section at a location spaced inwardly of the first guide means during all relative positions of the inner and outer boom sections, a third'guide means spaced outwardly on the outer boom section, said 7 extending and retracting means being adapted to move the second and third guide means parallel to one another and along a fixed, linear path in all positions of the outer boom section, a flexible strand attaching means on the fixed portion of the boom assembly, a flexible strand having one end wound about the winch and then running to the first guide means, inwardly to the second guide means, outwardly to the third guide means, and inwardly to the attaching means where the other end is secured, a load carrying device suspended from the flexible strand between the attaching means and the third guide means, said load carrying device having a sufficient weight to remain at a lower elevation than the attaching means and third guide means in all positions of the outer boom assembly.

9. The extensible boom assembly of claim 8 further characterized by and including a'fourth guide means pos'i? tioned on the outer boomsection between the third guide means and the attaching means in all relative positions of the inner and outer boom sections and positioned upwardly from the load carrying device, said third and fourth guide means and load carrying device cooperating to form an inverse loop of flexible strand therebetween.

References Cited in the file of this patent UNITED STATES PATENTS Bayard Jan. 6, 1925 1,522,408 2,166,447 Ruppenthal July 18, 1939 2,477,401 Billings July 26,1949 2,570,417 Wulleman Oct. 9, 1951 2,588,283 Osgood Mar. '4, 1952' 2,684,159 Oldenkamp July20', 1954 FOREIGN PATENTS 13,101 Great Britain June 23, 1899 France Dec. 14, 1933, 

